/*
 * Copyright 2012-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.autoconfigure.condition;

import org.springframework.context.annotation.Condition;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.StandardServletEnvironment;

/**
 * {@link Condition} that checks for the presence or absence of
 * {@link WebApplicationContext}.
 *
 * @author Dave Syer
 * @see ConditionalOnWebApplication
 * @see ConditionalOnNotWebApplication
 */
@Order(Ordered.HIGHEST_PRECEDENCE + 20)
class OnWebApplicationCondition extends SpringBootCondition
{

    private static final String WEB_CONTEXT_CLASS =
            "org.springframework.web.context." + "support.GenericWebApplicationContext";

    @Override
    public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata)
    {
        boolean required = metadata.isAnnotated(ConditionalOnWebApplication.class.getName());
        ConditionOutcome outcome = isWebApplication(context, metadata, required);
        if (required && !outcome.isMatch())
        {
            return ConditionOutcome.noMatch(outcome.getConditionMessage());
        }
        if (!required && outcome.isMatch())
        {
            return ConditionOutcome.noMatch(outcome.getConditionMessage());
        }
        return ConditionOutcome.match(outcome.getConditionMessage());
    }

    private ConditionOutcome isWebApplication(ConditionContext context, AnnotatedTypeMetadata metadata,
                                              boolean required)
    {
        ConditionMessage.Builder message =
                ConditionMessage.forCondition(ConditionalOnWebApplication.class, required ? "(required)" : "");
        if (!ClassUtils.isPresent(WEB_CONTEXT_CLASS, context.getClassLoader()))
        {
            return ConditionOutcome.noMatch(message.didNotFind("web application classes").atAll());
        }
        if (context.getBeanFactory() != null)
        {
            String[] scopes = context.getBeanFactory().getRegisteredScopeNames();
            if (ObjectUtils.containsElement(scopes, "session"))
            {
                return ConditionOutcome.match(message.foundExactly("'session' scope"));
            }
        }
        if (context.getEnvironment() instanceof StandardServletEnvironment)
        {
            return ConditionOutcome.match(message.foundExactly("StandardServletEnvironment"));
        }
        if (context.getResourceLoader() instanceof WebApplicationContext)
        {
            return ConditionOutcome.match(message.foundExactly("WebApplicationContext"));
        }
        return ConditionOutcome.noMatch(message.because("not a web application"));
    }

}
